What is an optical circulator?
The optical circulator has similar function and design as an optical isolator. An optical nonreciprocal circulator is a passive device that directs light sequentially from port 1 to 2 of port 2 to port 3, and so on in one direction only. The operation of a circulation pump is similar to that of an isolator except its constructions is more complex. As the insulator to fulfill their polarization using his task.
The typical structure of aThermostat consists of a series of walk-off polarizers, half wave plates and Faraday rotators. In general, an optical ciruclator has three or four ports.
A large number of circulators are available commercially. They have a low insertion loss, high isolation over a wide wavelength range, minimum polarization loss and low polarization mode dispersion.
The typical insertion loss of an insulator is about 0.6dB channel isolation is about 40dB optical return loss of 50dB andPolarization loss is less than 0.1 dB.
The applications of optical ciruclators
In advanced optical communications systems, are circulators for bi-directional transmission, WDM networks, fiber-amplifier systems and for optical time domain reflectometer (OTDR) measurements.
Optical circulators are essential compoents of optical transmission systems. They allow the transmission of light from an optical fiber or another waveguide to the direction of the baseLight propagation.
More information
Optical ciruculators extend the basic idea behind an optical isolator and add more functionality to the device. A thermostat is not disgard the backward propagating material of light, like an insulator, but it draws a different port, thus leading to a three-port device in the simplest configuration. Additional interfaces can be added if you want to light that divert from the third port to port quarter. Circulators are also six ports, the directLight in different ports in a circular fashion depending on which light enters interface.
You can guess that with the increase of the ports, the design of increasingly complex. You are absolutely correct on that to guess. A second layer of complexity is shared for polarization independent additional circulators because they have to the incident light from a port in the orthogonally polarized components and processes each component separately.
Typically, a thermostat requires a large number ofParts. The most important component in a polarization independent circulator is the beam displacement. Beam displacer made of a highly birefringent medium, so that it displaces the orthogonally polarized components spatially by different amounts.
Despite its complexity, optical circulators are available commercially in a relatively compact size with fiber pigtails at each end. Insertion losses are also very acceptable for such complex devices.
Optical circulators havefound many applications in the design of optical systems. An example would be a three-port circulator with a fiber grating in a narrow band pass filter used in the transfer work to realize. The thermostat coverts the device, a transmission filter for all practical purposes.
Without thermostat, have many applications through a fiber optic 3dB couplers, to introduce the 3dB loss will be replaced. The use of thermostats allows to realize the same goal with less than 1 dB insertion loss.
